用线性化近似方法,计算了具有色关联的色抽运噪声和色量子噪声驱动的光学双稳系统的 光强相对涨落,讨论了噪声间的关联和输入信号对光强相对涨落的影响,发现光强相对涨落随抽 运噪声强度和量子噪声强度的变化过程中存在极小值,且光强相对涨落与噪声间的关联程度密切 相关,但输入信号对其影响不大。

表面缺陷基态模孤子的性质在实现全光控制方面有重要的应用。基于非线性薛定谔方程，利用虚时间变换、非线性松弛法以及分步傅里叶算法等数值方法对具有半无限缺陷光格子的克尔型非线性介质中存在的基态模的特性进行了详细研究。研究结果表明：对于吸引型半无限缺陷光格子，表面缺陷基态模只能分布于缺陷处，而对于排斥型半无限缺陷光格子，表面缺陷基态模既可以分布于缺陷处，也可以分布于其他格子通道处；每个系统参数存在着一个临界值，当其他参数保持不变的情况下，这个系统参数的数值大于或小于其临界值时，表面缺陷基态模将能或不能分布于缺陷处。从物理机制方面看，光格子与光束诱导的非线性折射率之间的竞争导致了这种临界行为的出现。

Using linear approximation method, we calculate the intensity correlation time of a single-mode laser driven by both colored pump noise with signal modulation and the quantum noise with cross-correlation between its real and imaginary parts, and analyze the influence of the net gain coefficient a0 on the statistical fluctuation of the laser system. It is found that for the case that the colored pump noise is long time correlated, the main factor influencing the statistical fluctuation of the laser system is a0, and the frequency of the modulation signal has negligible effect on the statistical fluctuation of the laser system.

Using the linear approximation method, we study a single-mode laser system driven by colored pump noise and quantum noise with coupling between the real and imaginary parts when the laser is operated well above threshold. The steady state mean intensity fluctuation C(0) and signal-to-noise ratio (SNR) are calculated. It is found that there is a maximum in SNR when there is a minimum in the fluctuation of laser system if the coupling coefficient between real and imaginary parts of the quantum noise equals zero.

The phenomenon of stochastic resonance (SR) is found in a single-mode laser system driven by the colored pump noise with signal modulation and the quantum noise with cross-correlation between the real and imaginary parts. When the net gain a0 changes, it is found that, 1) the shape of the curve of the signal-to-noise ratio (SNR) versus the pump noise self-correlation time \tau exhibits a changing process of multiform SR, from single-peak SR to simultaneous existence of resonances and suppressions; 2) the curve of SNR versus signal frequency \Omega experiences a complicated changing process from the monotonous descending to the simultaneous appearances of a maximum and a minimum, and finally to monotonous descending; 3) the curve of SNR versus cross-correlation coefficient between the real and imaginary parts of the quantum noise \lambda_(q) appears an acute single-peak SR. Therefore, the net gain a0 greatly influences the characteristic of SR of laser system.